Did I trap moisture in crawl space insulation?

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Old 09-24-01, 06:09 AM
R
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Hi,

My question is something that has been bothering me since I did it. A year ago I was having trouble with a small crawl space that supports part of our kitchen. We were having trouble with wind infiltration up through the tile floor expecially along the baseboards. So, I went in the crawl space and saw some fiberglass insulation installed in the kitchen floor joists with the vapor barrier facing the crawl space (not facing the floor tiles). I covered the walls which were bare cement with 6 mil. poly sheeting to prevent drafts and I covered the vapor barrier with the poly as well. My question is: by installing the poly sheet between the crawl space and the vapor barrier, did I trap moisture and what are the potential problems?

I hope this enough info. To recap: the crawl space supports part of the kitchen but the walls are very porous. There is fiberglass insulation installed in the floor joists for the upper kitchen with the vapor barrier facing the dirt floor of the crawl space. I installed the poly sheeting on the bare walls to prevent drafts as well as up against the vapor barrier side of the insulation.

Thanks for any advice.

Robert Smith
 
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Old 09-25-01, 01:46 PM
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Originally posted by robert smith
Hi,

My question is something that has been bothering me since I did it. A year ago I was having trouble with a small crawl space that supports part of our kitchen. We were having trouble with wind infiltration up through the tile floor expecially along the baseboards. So, I went in the crawl space and saw some fiberglass insulation installed in the kitchen floor joists with the vapor barrier facing the crawl space (not facing the floor tiles). I covered the walls which were bare cement with 6 mil. poly sheeting to prevent drafts and I covered the vapor barrier with the poly as well. My question is: by installing the poly sheet between the crawl space and the vapor barrier, did I trap moisture and what are the potential problems?

I hope this enough info. To recap: the crawl space supports part of the kitchen but the walls are very porous. There is fiberglass insulation installed in the floor joists for the upper kitchen with the vapor barrier facing the dirt floor of the crawl space. I installed the poly sheeting on the bare walls to prevent drafts as well as up against the vapor barrier side of the insulation.

Thanks for any advice.

Robert Smith
 
  #3  
Old 09-25-01, 01:47 PM
rbisys
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Yes, you goofed. don't feel bad, most contractors don't know how to insulate a crawl space properly either.

The poly on the wall was good though. You don't say whether you have a poly on the dirt/rock. You should have a double layer crossed with 6" seam overlap. All you have to do now is tear out the fiber glass, it's probably worthless now and install a 97% efficient, 48" radiant barrier(RB) over the wall poly. Let it hang down to the ground. By placing the high efficiency RB on the wall your crawl space temp should be with in a few degrees of the upstairs. You will never have to worry about frozen pipes either. It will probably prevent any mold/mildew problems in your rugs or flooring. Mold/mildew can cause severe health problems, particularlly in children. You can find plenty of these fiber glass related health problems on the web. The moisture that gets trapped in the FG can rot out the joists. With or with out a poly.

Remove the fiber glass between the joists at the rim board. Replace it with a RB sheet too. Foam all holes and cracks and now you can seal off the vents.

Your crawl space must be as dry as possible. If you do not have positve drainage to a lower grade, install a sump pump.

Enter into your search engine; "radiant barriers" or "reflective insulation".

If you have any questions about method or material source, let me know.

Thank you for considering my opinion.

 
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